Electric attachment-plug.



PATENTED DEG. l2, 1905.

l E. E. STRONG. ELEGTEIG ATTACHMENT PLUG.

APPLICATION FILED APR. 3f 1905.

l IINITEI) sTATES PATENT OEEICE.

Specification of Letters Patent.

Patented Dec. 12, 1905.

Application filed April 3, 1905. Serial No. 253.537.

To` @ZZ whom it may concern:

Beit known that I, FREDERICK F. STRONG,

a citizen of the United States, residing at Bos-4 ton,in the county of Suffolk and State of Massachusetts, have invented an Improvement in- Electric Attachment-Plugs, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

My invention is an electric contact-making mechanism of the kind Icommonly known as attachment-plugs, having for its object the provision of means for securing quick screwlike action without twisting the cords and quickcertain electrical contact. Besides these objects are economy, simplicity, and durability of construction. This class of devices is used for many purposes, and especially by physicians for connecting their electrotherapeutical apparatus to the electric-light circuit by means of a connection which fastens into the socket normally occupied by an .incandescent-lamp bulb.y yThe two common types in general use are the so-called Edison and Thomson-Houston plug and the Westinghouse plug, the former operating by means of a screw-thread and causing great annoyance to the user because of the resulting twisting of the cords and the latter operating by means of holding-springs, which, however, allow more or less play and are liable to produce arcing. Accordingly I have devised a plug in which there are a plurality, preferably two, sets of short broken threads projecting from one part to enter the opposite part and be interlocked therewith by a quarter-turn, my device containing certain alining means and locking means, as well as a wiping contact or terminal, for giving certainty of electrical contact.

The constructional details of my invention will be understood from the following description, reference being had to the accompanying drawings, in which I have shown a preferred embodiment of my invention.

In the drawings, Figure l is a perspective view of the receiving part of my invention. Fig. 2 is a view in side elevation of the male portion or entering part of the invention. Fig. 3 is an end view of the latter, and Fig. 4 is a longitudinal sectional view of the part shown in Fig. 1.

It will be understood that the general features of the socket will be of any usual or preafter the manner of a bayonet-joint.

Projecting from this base 'is a tubular receiving portion b2, having a cylindrical lower part b3 and oppositely-deected portions b4, which are preferably set in on a smaller radius than the remaining portions b5 to operate somewhat These offset parts o* and b5 are of such proportions and so arranged that when the male part c (to be presently described) enters therein and is given a quarter-turn the portions of said part c which Occupied the larger circumference of the parts b will interlock snugly and immovably with the smaller parts b4 of shorter radius. In the portions o* I provide one or more screw-like depressions or broken threads b, opening freely at their outer ends o7, but preferably closed at their inner ends In". In other words, these threads do not extend entirely across the inwardly deiiected portions b4. Also I prefer to provide a short socket-like or cup-like depression 69 at one side or the other of the thread or threads o, herein shown at the side nearer the open end of the part b2.'

The part c or male member of the attachment-plug has a cylindrical body c for the greater part ofits length and preferably terminates in a slightly-tapered end c2. At its opposite sides, as herein shown, I provide projecting ribs or threads c3, corresponding in number and size and location to the female threads b before mentioned-z'. e., as herein shown, there are two of these threads in each group and two groups arranged opposite each other. Viewing Fig. 3, it will be seen that these threads project in Such manner as readily to enter the larger portions b5 of the tubular part of the socket-piece, so that when the male member is placed within the female member and given a quarter-turn the ribs c3 will t into the grooves 126, thereby quickly and firmly locking the parts together in screw fashion. Adjacent the rear end of the opposite groups of threads c3 I provide a projection c4, adapted to snap into the socket b9 before described. Also I prefer to provide one or more of the threads or grooves 56 just within its open end with a slight enlargement, as indicated at b1", and I provide the rear end of the corresponding rib or ribs with a slight enlargement c5, as clearly shown in Fig. 2, the result being that when the parts are turned into interlocking position these enlargements c5 snap into the yielding metal of the receiving portion b2, thereby locking the parts againstaccidental displacement. At its eX- IOO IIO

treme end the member c is provided with a Y conical contactor terminal c, and the base is provided with a spring-contact 612, having at its outer end a small conical hole Z213 for receiving the contact 06. The result is that when the male member cis put in place the pointed end of the terminal c6 instantly crowds into the tapering hole 613 of the yielding terminal Z212 and is given a wiping or rotary inward movement as the members c of the attachment-plug become interlocked. This insures a perfect contact, maintaining the contact parts 06 512 clean and in perfect order.

In use the member c is placed within the member b, the conical end c2 cooperating with the cylindrical portion bin guiding the parts quickly to proper position, it being understood that the threaded portion of the male member first enters the enlarged threadless portion of the female member. The parts are then given a quarter-turn over toward the right, thereby forcing the ribs c3 into the grooves b until the ends of said threads strike the ends bs of the grooves, and at the same time the enlargements c5 of the threads snap into the socket portions bw of the grooves, and the projections c'L similarly lock into the yielding sockets b, thereby making the parts absolutely fast. In accomplishing this movement the conical terminal c is caused. to wipe over with a cleaning action the surface of the yielding terminal 7212, thereby making perfect electrical contact. All this ymovement is accomplished by a quarter-turn, the extent of the turning movement depending, of course, upon the length of the threads and grooves.

I am aware that my invention is capable of many other embodiments coming within the spirit and scope of the claims, and accordingly I Wish it understood that I am not limited to the constructional details herein shown, except as otherwise specified in said claims.

My plug is adapted to incandescent lamps, apparatus of the kind previously mentioned, and various other uses.

Having described m-y invention, what I claim as new, and desire to secure by Letters Patent of the United States, is-

l. An electric attachment-plug, comprising cooperating parts adapted to t into each other and each provided with a plurality of indesof/,051

pendent threaded portions separated by longitudinal threadless portions, the containing part being tubular and having its threadless portions of greater radius than its threaded portions.

2. An electric attachment-plug, comprising' a tubular part having a plurality of narrow threaded portions extending longitudinally thereof and offset on a shorter radius than the intervening threadless portions of said part, and a cooperating part having projecting threaded portions corresponding to the threaded portions of the tubular part,said parts being provided with locking means, operating when the cooperating threaded portions are interoperative relation.

3. An electric attachment-plug, comprising a tubular part, and a cooperating part to enter the same, said two parts having a series of broken threads permitting direct longitudinal insertion of one part within the other part and becoming fully interlocked by a partial' relative rotation, said tubular part having a cylindrical inner end, andsaid cooperating part having a tapering forward end for fitting within the latter.

4. An electric attachment-plug, comprising a tubular part, and a cooperating part to enter the same, said two parts having a series of broken threads permitting direct longitudinal locked, for positively locking the parts in insertion of one part within the other part i to this specification in the presence of two subscribing witnesses.

FREDERICK F. STRONG.

Witnesses:

Guo. H. MAXWELL, M. A. JONES. 

